This application claims the priority of German patent application Ser. No. 198 49 859.4 filed Oct. 29, 1998. The disclosure of the German patent application, as well as that of each US and foreign patent and patent application mentioned in the specification of the present application, is incorporated herein by reference.
The present invention relates to improvements in apparatus for accumulating successive sheets of short or long series of sheets into piles or stacks of overlapping sheets at a stacking station, and for removing stacks from a sheet-gathering receptacle at the stacking station. More particularly, the invention relates to improvements in apparatus which can automatically remove successive freshly gathered stacks while the sheets continuously arriving at the stacking station gather into fresh or growing stacks of overlapping sheets. Apparatus of such character are known as sheet piling devices, and one thereof is described and shown in U.S. Pat. No. 4,436,472 granted Mar. 13, 1984 to Kunzmann.
The patent to Kunzmann discloses an apparatus wherein several stacking units are placed side-by-side. A drawback of the patented apparatus is that its design imposes limits upon the number of stacks or piles which can be gathered per unit of time with a requisite degree of accuracy. Moreover, the condition of the sheets is likely to be affected if the rate at which the sheets are supplied and stacked exceeds a relatively low threshold value.
Another drawback of conventional apparatus of the above outlined character is that they cannot be rapidly converted for the stacking of sheets having different sizes and/or shapes. This can result in prolonged interruptions of the operation and a considerable reduction of the output.
An object of the instant invention is to provide an apparatus which constitutes an improvement over and an advantageous further development of apparatus disclosed in the aforementioned U.S. Pat. No. 4,436,472 to Kunzmann.
Another object of the invention is to provide an apparatus which can be rapidly converted to gather larger or smaller, wide or narrower and/or shorter or longer sheets with the same degree of accuracy.
A further object of the present invention is to provide novel and improved means for manipulating one or more abutments for the growing stacks of paper sheets or the like.
An additional object of the invention is to provide a novel and improved method of manipulating successive sheets of a stream or flow of partially overlapping sheets in a stacking machine.
Still another object of the invention is to provide a sheet stacking apparatus which can gather sheets of different thicknesses and/or other characteristics with the same degree of accuracy and predict-ability.
Another object of the invention is to provide a novel and improved method of manipulating scalloped streams of partially overlapping paper sheets or the like preparatory to and during conversion or gathering into stacks or piles.
Still another object of the invention is to provide an apparatus which can be reliably converted for the processing of sheets having different sizes and/or shapes within short intervals of time.
The invention resides in the provision of an apparatus for gathering successive sheets of a series of sheets (such as paper sheets) into growing stacks which are being gathered in and, when fully grown, are removed from a receptacle at a stacking station. The apparatus comprises means for conveying successive sheets of the series (e.g., successive sheets of a scalloped stream consisting of partially overlapping sheets) in a first direction (e.g., substantially horizontally) into the receptacle at the stacking station to thus accumulate in the receptacle a growing stack of overlying or overlapping sheets, front and rear abutments or stops for the sheets of a stack in the receptacle (the abutments are spaced apart from each other in the first direction and the front abutment is movable relative to the receptacle between operative and inoperative positions), means for withdrawing fully grown stacks from the receptacle in the first direction while the front abutment dwells in the inoperative position, means for transporting withdrawn stacks in a second direction (e.g., substantially horizontlly and substantially at right angles to the first direction) , and means for adjusting the rear abutment in and counter to the first direction. The conveying means can comprise a belt or chain conveyor or another suitable conveyor which can deliver to the receptacle sheets having different lengths, and the rear abutment is adjustable for the purpose and to the extent necessary to conform the spacing of the front and rear abutments from each other to the lengths of sheets being conveyed to the receptacle.
The apparatus can further comprise a platform which can resemble or constitute a rake and serves to separate the sheets. The platform is movable with the conveying means between a plurality of positions, such as forwardly and backwards (as seen in the first direction) and/or up and down. The movements of the platform in and counter to the first direction can take place in synchronism with movements of the withdrawing means (the latter can include gripper or holder means adapted to engage the front end portion of a fully grown stack and to pull the stack from the receptacle while the front abutment is maintained in its inoperative position).
The conveying means is or can be arranged to share the movements of the platform between a plurality of different levels.
In accordance with a presently preferred embodiment, the apparatus further comprises a carriage (such as a slide) for the aforementioned platform and for the conveying means, as well as an elevator which serves to move the carriage between a plurality of different levels. The carriage is movable (preferably relative to the elevator) in and counter to the first direction, and the elevator is movable up and down relative to the receptacle at the stacking station.
The mounting of the platform on the carriage is or can be such that the platform is movable relative to the carriage in and counter to the first direction through distances corresponding to the extent of adjustment of the rear abutment relative to the front abutment.
The forward end of the sheet conveying means is preferably disposed at a predetermined (fixed) distance from the platform.
The receptacle can be provided with an exchangeable bottom wall, and such bottom wall can include an exchangeable substantially strip-shaped holder as well as a plurality of sheet supporting rakes carried by the holder. The holder can further carry lateral stops and guide means for the lateral stops.
The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved apparatus itself, however, both as to its construction and its mode of operation, together with numerous additional important and advantageous features and attributes thereof, will be best understood upon perusal of the following detailed description of certain presently preferred specific embodiments with reference to the accompanying drawings.